Conventional systems for controlling the synchronization of a camera and a motor drive unit generally lack the capability to detect abnormal movement of film within the camera. This synchronization between the film winding mechanism and the motor drive unit has been assumed to be equivalent to that between the film and the film winding mechanism. In practice, however, one cycle of normal film winding operation does not always lead to advancement of the film by exaclty one frame. Accordingly, the mere detection of whether or not the precise synchronization between the film winding mechanism and the motor drive unit is established cannot ensure the exact advancement of the film. Aside from the attainment of proper phase synchronization between the film winding mechanism and the motor drive unit, the system is required to be capable of ensuring proper speed synchronization between the film and the film winding mechanism.
In the latter connection, it should be explained that when the film slips or jams at the take-up spool, for example, there is a likely possibility that idle rotation of the sprocket will occur which results in none of the film being advanced. In these circumstances, the camera will nevertheless be ready for the next frame exposure because of the complition of one cycle of winding operation.
Another problem occurs when the film winding mechanism is no longer effective to advance the film through the full lenght of one frame due to the completion of exposures of all of the available frame areas; an excessive tension is exerted on the film and the sprocket teeth may damage the film perforations. Upon occurrence of the prescribed amount of rotation of the sprocket, the camera is set to the cocked position at which the shutter is ready for the next exposure. This occurs despite the lack of availability of a fresh film area of sufficient format. It is clear that mere detection of whether or not the motor drive unit moves the camera mechanism through one cycle of operation is inadequate in controlling the synchronization of the shutter cocking and film winding mechanisms with the motor drive unit.